The Gnutella-based download client LimeWire has ceased all its operations after a U.S. federal judge granted a request from the RIAA. Limewire was ordered to disable all functionalities in the current application to prevent users from sharing copyrighted material. The verdict is expected to have an unprecedented impact on the P2P file-sharing landscape.

A few months ago the RIAA asked a New York District Court to shut down the world’s most installed file-sharing application, LimeWire.

The record labels argued that the Gnutella-based download client might have caused billions of dollars in lost revenue and that it’s therefore one of the largest threats to the music industry’s revenue. Today, RIAA’s request was granted by a federal judge.

According to the injunction, Limewire “intentionally encouraged infringement” by Limewire users, it is used “overwhelmingly for infringement” and it knew about the “substantial infringement being committed” by its users.

The evidence further showed that Limewire marketed its application to Napster users and that its business model depends on mass copyright infringements.

The New York District Court demanded that Limewire shuts down its entire operation, including all searches and uploading and downloading that occurs through the client. LimeWire users who start up their client will immediately notice that it is no longer usable.

Limewire’s in-client notice to users.

The outcome of this case could potentially change the file-sharing landscape for good. Despite BitTorrent being the leading file-sharing protocol for several years already, LimeWire is most likely the most installed P2P application on the market. In 2008 LimeWire was the most installed P2P application with an impressive market-share of 37%, compared to 14% for runner-up uTorrent.

Now the RIAA has scored a victory in court against LimeWire, millions of people will have to seek an alternative download client, which might mean a significant boost in user numbers for some of the major BitTorrent applications.

On the other hand, software that’s similar to LimeWire might be affected negatively by today’s judgment. In the injunction software such as FrostWire and MP3Rocket, but also BitTorrent clients including uTorrent, Vuze and Transmission are described as “similar software”. Could one of these become the next target?

In a response to TorrentFreak, the RIAA didn’t want to speculate on future targets. Instead, we were told: “The court has now signed an injunction that will start to unwind the massive piracy machine that Limewire and Gorton used to enrich themselves immensely.”

“In January, the court will conduct a trial to determine the appropriate level of damages necessary to compensate the record companies for the billions and billions of illegal downloads that occurred through the Limewire system,” the RIAA added.

Although today’s decision is the end of Limewire as we know it, the brand is expected to reappear soon with a “non-infringing” service.